This represents the third in a series of conferences held every three years under the auspices of the Keystone Symposia. Tumor Immunology is at a pivotal point in its maturation. Several melanoma derived antigens recognized by T-cells have been cloned (MAGE 1, MART 1/Melan-A, gp100, tyrosinases, gp75), vaccine trials have been initiated and nascent gene therapies using cytokines or tumor antigens are underway or will be initiated soon. Problems in realizing immunotherapies are increasingly focusing on the molecular mechanisms involving tumor escape from immune recognition including alterations in T-cell signalling, lack of susceptibility of tumors to apoptotic induction, failure of tumors to process and present antigen in an immunogenic manner. Cytokines are increasingly being studied in the context of targeted disruption of cytokine genes, cytokine gene therapy and cytokine administration. interleukin 12 in particular has been identified as an extremely important cytokine in regulating the immune response and in promoting cellular immunity with dramatic antitumor responses in murine models. Interleukin 10 is suspected to be important as well in escape from immunity. The major pivotal problems in this field are l) Defining new molecular targets, 2) identifying the molecular mechanisms with escape of tumors from immune recognition, and 3) devising clinical strategies that would realize important gains for cancer patients. The meeting will bring together molecular biologists, cytokine researchers, animal experimentalists, protein biochemists, clinical oncologists and immunologists all of whom share an interest in moving clinical questions into the laboratory and rapidly assessing novel therapies based on sound immunologic principles. They will jointly redefine the major new problems, discuss new information lately available in tumor immunology, and construct the next set of critical questions which need to be addressed in the future.